Self-synchronization of television scanning means



P 1939. K. SCHLESINGER 2,173,502

SELF-SYNCHRONIZATION 0F TELEVISION SCANNING MEANS H Filed Au 6, 1957 s Sheets-Sheet 1 P 1939. K. SCHLESINGER 2,173,502

SELF-SYNCHRbNIZATION Of TELEVISION SCANNING MEANS Filed Aug. 6, 1937 3 Sheets-Sheet 2 /n ventor:

WIS-1M Sept. 19, 1939. K. SCHLESINGER 7 SELF-SYNCHRONIZATION 0F TELEVISION SCANNING MEANS Filed Aug. 6, 1937 5 Sheets-Sheet 3 Fly. 6

Mf/W

Patented Sept. 19, 1939 UNITED STATES SELF-SYNCHRONIZATION OF TELEVISION SCANNING MEANS Kurt Schlesinger, Berlin, Germany, assignor to Radioaktiengesellschaft D. S. Loewe, Berlin- Steglitz, Germany Application August 6,

1937, Serial No. 157,722

In Germany August 21, 1936 Claims.

I. synchronization impulses for the image change and line change to be produced automatically by the scanning point when it scans the surface of the image. The fundamental advantages of this so-called automatic or self-synchronization 9 are well known. The present device refers to a particularly suitable optical arrangement, which operates with a glass border having suitably confined edges. The method is capable of being employed for scanning means having a Nipkow disc, reflectors or a lens disc as well as scanning means which employ for scanning purposes a reproduction of the luminous screen of the Braun tube.

The present invention is illustrataed in the accompanying drawings in which Fig. 1 shows diagrammatically a device for producing line synchronization impulses and Fig. 2 a similar device for producing frame synchronizing impulses.

Figs. 3 and 4 show similar devices for special cases.

Fig. 5 is a synchronization device for the same transmitter and Fig. 6 for a transmitter having a cathode ray tube for scanning.

In Fig. 1 there is shown a diagram of an embodiment of the invention. An objective I projects in the manner known per se a sharp reproduction of the light point moving in the scanning means area 2 (disc, screen of the Braun tube or the like) on the image frame 3 to be scanned. A plano-parallel sheet of glass 4 disposed on the side edge of this scanning area possesses at 5 a polished and ground edge of such inclination that the light ray, when it meets against this edge, is totally (or by a silver coating) reflected into the interior of the sheet and, owing to further total reflections at the walls of the glass sheet, is compelled to remain in the sheet until it reaches an outlet edge 6 and passes via a collecting lens of high refractive power (hemispherical lens)- 1, which also may be cemented to the edge into the photo-cell 8. This photo-cell accordingly receives brief line impulses which may be amplified by the special high-frequency amplifier 9. The photo-cell l0 arranged behind the frame 3 and acting on the normal image amplifier ll transmits the contents of the image. It will be clear that the two channels 8, 9 and Ill, II will always be lighted but alternately, so that a mutual interference of both signals is quite out of the question. It

is therefore possible to provide a common amplifier for both photo-cells, which is indicated by the bracket l2. This single amplifier must then be apt for the entire frequency band entering into the question.

That which is set forth in Fig. 1 in respect of the line change impulses may also be performed in respect of the frame change impulses. For this purpose, as shown in Fig. 2, there is disposed beside the glass sheet 4 already described a second peculiarly shaped glass sheet l3 on the upper (or lower) edge of the screen 3. This sheet is provided with a reflecting edge [4 like edge 5. When the light ray impinges on this edge l4 it takes, insidethe glass again reflected at the edge I 5, the way 130., I31) and impinges via the common lens 1 the same photo-cell 8."

An amplifier which, following on 8', has to amplify synchronization impulses of both kind must include also middle frequencies in its frequency band, the image change impulses being of the order of 10 seconds; assuming the line impulses amounting to 10- seconds. Even in this case the amplifier may be so constructed that it does not transmit frequencies which are lower than 10 such as'represented by mains humming and microphone effect.

The glass sheets 4 and [3 may also be curved. They must have a particular form in those cases in which the scanning my does not impinge on the image area 3 vertically, but at an acute angle. Cases of this kind occur in particular-in conjunction with transmitters: havingra Nipkow disc for interlaced scanning, wherein according to Fig. 3 for correcting the key-stone distortion the disc I! and image plane 3 are arranged at a certain angle of inclination a in relation to the ray l6.

According to Fig. 4 there are provided also in this case a glass border 13 for the frame change and 4 for the line change on two edges of the image frame 3. Owing to the geometric arrangement, however, the latterborder will have the form shown in Fig. 4, as owing to the inclinationu (Fig. 3)- the ray 5a no longer leaves the edge 5 vertically thereto, but obliquely. The frame glass sheet may remain as described above. Both rays are collected by the objective 1 and conducted to the synchronization photo-cell 8.

The described reflex method is not limited to television decomposing means of that kind which scan an inclosed image 3, but is also capable of use when a remote object area is to be scanned. 5

(Openair scanners, etc.). The optical arrangement which is employed in this case is shown in Fig. 5. There is first produced with the aid of the objective I a sharp intermediate image 3 of the frame 2 of the Nipkow disc or the like. At 3 there are arranged the reflex borders 4 and I3 which, when impinged by the ray, conduct sharply defined synchronization impulses via the collecting lens I to the synchronization cell 8 connected to the synchronization amplifier 9. The greater part of the light, which does not impinge on the edge of the reflex frame, is transmitted through the free intermediate image plane 3. These rays reach a second objective l8 reproducing the intermediate image plane 3, and accordingly also the frame 2, sharply on the object plane l9. In this plane there may then be situated in the usual manner either the object to be reproduced, which excites for example by reflection the image cells Ill connected to the image amplifier II, or there may also be arranged for example the photo-electric mosaic screen of an electron ray tube, which in turn receives the light of an openair scene by way of a special reproducing objective located on the opposite side and is scanned and discharged point by point by the electronic ray. In all these cases there is ensured by the reflex method according to the invention an automatic or self-synchronization, which possesses the known advantage that the linearity of the image screen is of the same quality as the linearity of the ground edge of the reflex frame and is independent of any division errors.

It is also possible, to use the deflecting glass sheets when light source and scanning means 2 are represented, according to Fig. 6, by the luminous screen of a Braun tube 2! scanned in lines in a well known manner. 23 is the luminous layer covering the glass plate 22 and projected by an objective [9 for example on a moving film 3. Two adjacent edges of plate 22 are provided with reflecting shets 24 (only one is shown) corresponding to 4 and I3 of Fig. 4, which are covered also with a fluorescent layer. When the electron ray impinges one of the sheets 24 the secondary light is deflected by the oblique edge of 24 and conducted by the lens 1 into the photo-cell 8.

I claim:

1. An arrangement for producing synchronizing impulses in television scanning devices providing a scanning device moving a light beam linewise over the area to be scanned, one photoelectric cell controlled by the image element brightness, a second photo-electric cell for producing the line and image synchronizing impulses controlled from said scanning light beam, a reflecting device consisting of two reflecting planes inclined under 45 against the image area, one inclined reflection plane being arranged at one edge of the image the other reflection plane being arranged at the edge perpendicular to the first.

2.- An arrangement for producing synchronizing impulses in television scanning devices providing a scanning device moving a light beam linewise over the area to be scanned, one photoelectric cell controlled by the image element brightness, a second photo-electric cell for producing the line and image synchronizing impulses controlled from said scanning light beam, a reflecting device consisting of a glass block with two reflecting planes inclined under 45 against the image area, one inclined reflection plane being arranged at one edge of the image the other reflection plane being arranged at the edge perpendicular to the first.

3. An arrangement for producing synchronizing impulses in television scanning devices providing a scanning device moving a light beam linewise over the area to be scanned, one photoelectric cell controlled by the image element brightness, a second photo-electric cell for producing the line and image synchronizing impulses controlled from said scanning light beam, a reflecting device consisting of a glass block with two reflecting planes inclined under 45 against the image area, one inclined reflection plane being arranged at one edge of the image the other reflection plane being arranged at the edge perpendicular to the first, and a further reflecting plane reflecting the light beam of the one scanning area edge in the same direction as the light beam reflected of the other edge.

4. An arrangement for producing synchronizing impulses in television scanning devices providing a scanning device moving a light beam linewise over the area to be scanned, one photoelectric cell controlled by the image element brightness, a second photo-electric cell for producing the line and image synchronizing impulses controlled from said scanning light beam, a reflecting device consisting of a glass block with two reflecting planes inclined under 45 against the image area, one inclined reflection plane being arranged at one edge of the image the other reflection plane being arranged at the edge perpendicular to the first, and a further reflecting plane reflecting the light beam of the one scanning area edge in the same direction as the light beam reflected of the other edge, and a concentrating lens which the light beam concentrates.

5. An arrangement for producing synchronizing impulses in television scanning devices providing a scanning device moving a light beam linewise over the area to be scanned, one photoelectric cell controlled by the image element brightness, a second photo-electric cell for producing the line and image synchronizing impulses controlled from said scanning light beam, a reflecting device consisting of a glass block with two reflecting planes inclined under 45 against the image area,'one inclined reflection plane being arranged at one edge of the image the other reflection plane being arranged at the edge perpendicular to the first, and a further reflecting plane reflecting the light beam of the one scanning area edge in the same direction as the light beam reflected of the other edge, and a concentrating lens bywhich the light beam is concentrated, the reflecting device being arranged in the plane of an intermediate image.

KURT SCHLESINGER. 

